Governing mechanism for extraction type steam turbine



Nov. 19, 1957 J. M. BAKER 2,813,400

GOVERNING MECHANISM FOR EXTRACTION TYPE STEAM TURBINE Filed Aug. 17, 1956 2 Sheets-Sheet 1 JACK M. BAKER HIS ATTORNEY Nov. '19, 1957 J. M. BAKER 2,313,400

GOVERNING MECHANISM FOR EXTRACTION TYPE STEAM TURBINE Filed Aug. 1'7, 1956 2 Sheets-Sheet 2 INVENTOR JACK M. BAKER BY HIS ATTORNEY United States Patent GOVERNING MECHANISM FOR EXTRACTION TYPE STEAM TURBINE Jack M. Baker, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application August 17, 1956, Serial No. 604,688

9 Claims. (Cl. 60-67) This invention relates to governing mechanism for an elastic fluid turbine, specifically a steam turbine of the extraction type, having an inlet valve controlling the admission of steam to a first high pressure turbine section in series flow relation with one or more lower pressure turbine sections, some of which have a valve for regulating the pressure of steam extracted from the turbine by altering the flow of motive fluid to successive lower pressure sections of the turbine. This invention is a further improvement on the so-called three-arm type of extraction governor disclosed in U. S. Patent 2,111,420, issued March 15, 1938, on an application of F. R. Ericson and E. D. Dickinson.

In recent years the extraction type steam turbine has become popular for application in industrial plants such :as paper mills or chemical factories where substantial quantities of electric power are consumed and there is :great need for steam at various pressures for heating and other process purposes. Such an industrial plant can often generate its own electrical energy at less cost than purchasing it from a public utility; and process steam at various pressures may be conveniently obtained by employing an extraction turbine having an appropriate number of sections with controlled extraction conduits having valves actuated by pressure governors for keeping constant at desired values the pressure of the steam extracted from the various sections. In some of such plants, it has been found desirable to use extracted.

steam in heat exchangers for raising the temperature of the water going into the boiler. This may be accomplished etiiciently by extracting the feedwater heating steam from a low pressure section of the turbine. Since, in plants having a boiler supplying a single turbine, the steam requirements of the feedwater heater will bear a definite relation to the total flow of steam entering the turbine, it has been found possible, by means of the improvement in the three-arm governing mechanism described herein, to avoid the need for a pressure governor plying the electrical needs of the plant, must be'maintained essentially constant at a desired value, unaffected by the variable requirements of steam taken through the controlled extraction conduits (i. e. those in which the pressure is controlled by apressure governor) and the uncontrolled extraction conduit (having no pressure governing device) supplying the feedwater heater.

Accordingly, an object of this invention is to provide an improved form of extraction turbine governor capable of maintaining constant the mechanical power output of the turbine irrespective of variable extraction of steam from a turbine section having no pressure governor for regulating the pressure of the extracted steam.

A further object is to provide an improved extraction governor of the type described particularly adapted for supplying steam to a feedwater heater without the addiis represented by the valve 4d.

ice

tiofial complexity .of a pressure governor and extraction valve for controlling the pressure of such feedwater heating steam,

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings in which:

Fig. l is an improved three-arm extraction governor incorporating the invention in its simplest form as applied to aturbine having only two sections; Fig. la is a diagrammatic illustration of the method of operation of the three-arm governor of Fig. l; and

Fig. 2 represents the application of the invention to a turbine having three sections with two controlled extraction openings (each having a separate pressure regulator) and one uncontrolled opening (having no pressure regulator).

Generally stated, the invention is practiced by providing the three-arm governing mechanism with modifying linkage means which positions the three-arm lever in the same manner as the speed governor, the increment of motion produced by this linkage being a function of changes in pressure in the turbine section immediately upstream from that from which the uncontrolled extraction is taken.

Referring now more particularly to Fig. 1, the invention is illustrated as applied to a steam turbine plant comprising a two-section turbine illustrated generally at 1, driving an electrical generator 2 and supplied with steam by a suitable boiler 3. The boiler supplies motive fluid by way of conduit 3a to the high pressure turbine section In, as controlled by inlet valve lb. The second turbine section 10 is supplied with motive fluid ata variable rate by means of the extraction valve 1d. Process steam is extracted at a variable rate from the low pressure end of the first turbine section in by way of a controlled extraction conduit 4, at a rate determined by the requirements of the consumer 4a, represented for instance by the valve 411, and at a constant pressure maintained by the pressure governing device 11, the action of which is described more particularly hereinafter. It is the presence of this pressure governor 11 which makes the conduit 4 a controlled extraction conduit. Condensate exhausted from the consumer 4a is returned by conduit 5 to the feedwater heater 6, which is connected by conduit 6a with the boiler 3. There will usually be some loss of steam in the consumer 4a, so that the quantity of condensate returned through conduit 5 is not the same as that received through conduit 4. This inevitable loss is represented by the vent conduit 40 and the quantity of flow therethrough It is to be noted that the quantity of this leakage is a function of the nature and operating condition of the consumer 4a, and that this leakage will ordinarily be substantially constant in plants of the type for which the invention is intended, so that the quantity of steam or condensate returned through conduit 5 will be a fairly definite known function of the steam received through conduit 4.

In accordance with the invention, the heat source for the feedwater heater 6 is steam extracted from the last turbine section Is, as represented by the uncontrolled extraction conduit 6a communicating with the turbine section 1c at a location where the pressure is appropriate for the needs of the feedwater heater. It will be appreciated by those familiar with the art that the flow of steam through conduit 6a to the feedwater heater 6 is regulated by a suitable device (not shown) which may, for instance, be responsive to the temperature of the feedwater leaving the heater through conduit (in. The precise means used to control the operation of the feedwater heater 6 is not a part of this invention, but is represented diagrammatically by the valve 6b. Thus it will be appreciated that the uncontrolled extraction" through conduit 6a is at a rate determined by the independent requirements of the feedwater heater, and not under the control of a pressure governing component ofthe three=arrn governing mechanism described herein. Thisfiow is" not a constant function of the rate of steam flowing through the low pressure turbine section its; but is rather afunction of the total flow of steam supplied} to the turbine, which of course varies by reason'of the variable-requirements of the consumer 4a. 7

Thus it will be seen that the term uncontrolled extraction, as used herein, means that the turbine gave-m ing system includes no pressure responsive regulating valve for determining the pressure of the steam extracted, i; e;, the turbine governor has no contr-ol over the extraction steam but must act properly irrespect'ive of the quantity of steam taken from the uncontrolled extraction stage; Thus, conduit 4represents controlled extraction since it has an associated pressure governor-'11, and conduit 6a represents uncontrolled extraction?" having no pressure governor incorporated as part of the" turbine governing mechanism.

' The steam exhausted from the low pressure turbine section 10 is received by condenser 7-, whence the" condensate is returned by boiler feed pump 8 through conduit a. It will be understood that the pump 8 is a diagrammatic representation of pump means for getting all the condensate back into the boiler. Actually; the conduit 5 could conceivably discharge into the condenser 7, depending on the temperature and pressure conditions at which the fluid is exhausted from the consumer 4a. It need only be noted here that suitable pump means is provided for returning the exhaust from the consumer 4a and the condensate from condenser 7 to the feed-water heater 6.

\ It will now be seen that the total flow of steam into the turbine is a joint function of the mechanical power required by the load generator'Z, and of the process steam required by the consumer 4a, and of the demand for heating steam in the feedwaterheater 6, which latter is in turn a function of the total steam flow from the boiler. This interrelation of variable factors resultsin avariable demand for steam in the feedwater heater, which necessitates a modification in the three-armgovern-- ing mechanism in order to avoid undesirable fluctuations in the mechanical power output available to the generator 2.

As described more completely in the above-mentioned Ericson et a1. Patent 2,111,420, the basic three-arm g-overnor comprises a T-shaped floating lever member,.s hown at 9 in Fig. 1 herein, interconnectingthe speed governor, the extraction pressure governor, and the main inletvalve and extraction valve. The flyball speed governor 10 is driven at a speed proportional to the turbine rotor speed,v and is connected to position the fulcrum pivot 9a of the three-arm lever 9 as a fu'nctionof the mechanicalipower output required by the load generator 2. The extraction pressure governor 11 is responsive; to thepressureof steam extracted through the controlled extraction conduit 4, by reason of the pressure-sensing conduit 11a, and has an output rod 11b connected by pivot 91; to one arm of the three-arm lever 9. Another arm is connected at pivot 90 to position the actuating rod of inletval-ve 1b. The third arm is connected by pivot- 9d to position the extraction valve 1d. a I

It will be understood by those acquainted with extraction governors of this type that the general operation is that the governor 10 moves the pivot point 9a up and down so that the valves 1b, 1d are moved in the same direction, that is, both valves open orbotht close, simultaneously to increase or decrease the" steam flow through the turbine, as required by variations in the demand for mechanical power output, while the pressure governor 11 causes the three-arm lever 9 to rotate about the fulcrum 9a, moving valves 1b, Id in opposite directions',. onevalve opening while the other closes, in order to controlthe pressure of the steam extracted through conduit 4. The

designof. the linkage is such that the mechanical power output will remain constant as determined by the setting of the speed governor 10, while the extraction pressure in conduit 4 will remain constant as determined by the setting of the pressure governor 11. The speed setting of governor 10 is represented diagrammatically by a synchronizing screw 10a which carries the movable fulcrum 1 06 the position or which determines thesp'eed which will be heldby the governor 10. Of course, appropriatemeans may be provided also for adjusting the pressure which will be held by the pressure governor 11.. Such details do not form a part of the present invention and need not: be described further here.

In accordance with the invention, the governor 10 is not connected directly to the three-arm fulcrum pivot 9a but has interposed therebetween a special modifying linkage indicated generally at 12. This linkage comprises a lever 1222 having, an intermediate pivot connected by link 12b to the fulcrum 9a, and a first end pivot connected by link-12c to the left-hand end of speed governor lever 10c; The other end of lever 12a is connected by link 12d toa' bell-crank arm He, the other arm 12 of which is forked so: as to straddle the pressure governor actuating rod 11b. A compression spring 13 biases thebell-crank arm 12 counterclockwise into engagement with a stop member represented by a transverse abutment pin 11c projecting from the red 1111. The action of the spring 13 is to maintain arm 12f alwaysin contact with the abutment 11c sothat ordinarily the bell-crank 12c will behave precisely as if it were pivoted to follow the motion of the rod l lb. The purpose of this breakaway connection is't'o permit the modifying; linkage to be disconnected 15y turning: the lockout screw 14 so as to move bellcrankarm- 12f to the right against the bias of spring 13 so as toremain out of contact with the abutment 110. In ordinary'operation-,,the lockoutscrew 14 will be backed OK to the left, as shown; in Fig. 1, so as to have no effect on the bell-crank, which will then follow the motion of the pressure governor rod 11b.

It Will-beseen'trom Fig.1 that the effect of this modifying linkage 12 is to cause the three-arm fulcrum 9a to be positioned in a vertical path as a function of the action of the speed governor 1'0 and by an additional increment eifected by thepressure governor 11.

The operation ot the modified three-arm governor illustrated in Fig; 1 is as follows. Assume first that the boiler is supplying steam to the turbine without the feedwater heater 6 in operation, and with no steam being extracted through the conduit 4. For this condition the pressure governor rod 1111 will be in a fixed position and the lockout screw 14 will be holding bell-crank 12f in a fixed position, away from abutment 110. The speed governor 10 willnow" move the fulcrum point 9:: vertically so as to position the inlet. valve 1b and extraction valve 121' inthe same direction by proportional amounts, since e111 the flow through the inlet valve 1b is also flowing through the extraction valve 1d into the low pressure turbine-section 1c.

It now it is desired to extract steam for the consumer 4a, but with the feedwater heater 6 still inoperative, the lookout screw 14- will be maintained against the bell-crank arm 12 to hold it to the right, away from abutment 110, so that the linkage 12 is disabled. Pressure governor 11 will' now respond to the varying pressure in extraction conduit 4 in accordance with the varying demand of consumer 4a and cause the three-arm lever 9 to rotate about the fulcrum point- 921 to position the inlet valve 1b and extraction valve. 1d differentially (in opposite directions) s6 as to maintainconstant the extraction pressure, as described more particularly in the above-mentioned patent to Ericson et a'l.-'--2,1'11,420-.

Now assumethat the valve 6b is opened to admit steam at varying rates as required by the feedwater heater 6.

The pressure governor 11 will try to adjust the valves 1'11, Id so as to maintain cons tant the extraction pressure in conduit 4. However, thevariable uncontrolled extraction through conduit fiameans that a 'large demand for steam in the feedwater heater 6 will deprive the lower pressure stages of the second turbine section 10 of motive fluid, and therefore tend to result in inadequate mechanical power output. .To compensate forthistendency, the lockout screw 14 is backed away from the bell-crank arm 12 so that it is free to follow the abutment 110. The operation is now as follows. i 1 t Assume that, with the linkage in thecondition shown in Fig. l, the feedwater heater control valveob should open to admit more steam to the feedwater'heater; Thus deprived of a portion of its motive fluid, the turbine rotor will tend to slow down, with: the result thatl thelfiyweights of governor 10 move inwardly so that pivot: point 10d rises. Link 100 pivots clockwise aboutthe fixed righthand end pivot 1% so that link 120 causes the left-hand end of lever 12a to rise, and link 12b moves the fulcrum pivot 9a vertically upwardly. Y

Referring to Fig. la, assume thatthis motion results in the three-arm lever 9 moving from the sposition indicated by the solid line A to the new broken line position identified B, which is essentially parallel to A. i This has the effect of opening both inlet valvevlb andextraction valve In, by proportional amounts. Opening the inlet valve 1b of course has the effect of admitting more motive fluid so as to increase the power output of the high pressure turbine section In. This will tend to bring the rotor speed hack to the normal value for which the governor synchronizing screw 10a is set. Opening movement of the extraction valve 1d will also increase the flow into the low pressure section 1c, as required by the increased feedwater heater demand. For an increase in demand for steam in the feedwater heater 6, and likewise for an increase in demand for mechanical power output, the control system responds to satisfy these demands, within normal speed regulation of the speedgovernor 10, while keeping constant the controlled extraction pressure in conduit 4. But nowassume operation at line A and a constant demand for mechanical power output. Then an increase in the demand for steanrin controlledex traction conduit 4 will decrease the pressure transmitted to the pressure governor 11, causingthe spring 11d to move the bellows abutment. lle to the right, so that actuating rod 111: pulls on pivot 9b torotate the three-arm lever clockwise about fulcrum pivot 9a. Thus, again referring to Fig. In, if operatinglwith three-arm lever 9' in position A without the invention 1 (with lockoutfscrew 14 holding bell crank 12 inla fixed position away from abutment 110), the three-arm l'ever would rotateabout fulcrum 9a to position C, This would open the inlet valve 1!; to increase steam flow to the turbine .la, and would somewhat close extraction valve 1d:to decrease steam flow to the low pressure turbine section 1c, so.that the differential between steam flow to section 1a and that to section 1c is sufiicient to satisfy the increased steam demands in the controlled extraction conduit 4. This decrease in steam flow to the low pressure turbine section 10 occurs at a time when an increased flow of steam-is required to feedwater heater6 (due? to the increase. in steam flow to section In). Furthermore, the total mechanical power output of the turbine sections 1a, lc will drop due to the diversion of steam through. conduit 6a. However, with the invention in operation (lockout screw l backed off to the left, permitting bell-crank 12 to follow abutment 11c), simultaneous with the increased flow of controlled extraction steam in conduit 4, the motion to the right of rod 1111 causes abutment 110 to move bell-crank 12 12c clockwise so link 12drisesandpulls upwardly the right-hand end of lever 12a. The threearm lever 9 now moves directly from position Asin. Fig. 1a to position D, with the increased controlledextraction demand in conduit 4 and the uncontrolled extraction demand in feedwater heater 6- both satisfied, and withthe same-mechanical power output as before. It is to be noted j 6 l I thatthis change is effected with no change iequired in speed. of the turbine or in position of'the speed governor lever 100. Thus the modifying linkage means 12 has the effect of causing link 12b to move upwardly by an increment such that the three-arm lever 9 assumes the position identified D in Fig. 1a, solely under the action of the pressure governor 11 and without change in the condition of speed governor 10.

Stated another way, the compensator 12 has the net eflect of altering the ratio by which the inlet valve 1b is opened for a given opening motion of the extraction valve Id. In Fig. In, it can be seen that the valve-opening movement of point 90, in going from position A to position D (with the modifying linkage 12 in operation) is greater than its movement from position A to position B; while the opening movement of point 9d, in going from A to D, is less than its movement from A to B. This means that the operation illustrated in Fig. 1a could be achieved also by shifting the fulcrum pivot 9a towards the right-hand pivot 9d. With the fulcrum 9a so relocated, it will be apparent that rotation of the three-arm by the pressure governor 11 would cause a proportionately greater movement of inlet valve 1b than the corresponding motion produced on extraction valve 1d.

The extra increment of opening motion thus commun cated to inlet valve 1b due to change in controlled extraction demand in conduit 4, supplies the additional motive fluid required to satisfy the increased extraction demand from the feedwater heater 6, while maintaining the extraction pressure in conduit 4 at the preset value, with out reducing the mechanical power output to the generator 2 and without causing the speed of the turbine-generator to change. Thus by proper design of the linkage described above, the conventional three-arm type of governor can be made to keep the mechanical power output constant with changes in controlled extraction demand and irrespective of changes in the uncontrolled extraction from the low pressure section 1c to the feedwater heater 6.

Fig. 1 is only a very diagrammatic showingcf one form of the invention. In an actual machine, the speed governor 10 would position the pilot valve of a hydraulic servo-motor which would in turn position the fulcrum pivot 9a. Likewise, the pivots 9c, 9d would be connected to position the pilot valves of servo motors which would furnish the power required to position the steam valves 1b, 1d. Such details of the actual mechanism have been omitted for the sake of clarity.

Likewise, it will be seen from the above that the invention may be practiced by physically shifting the pivot 9a closer to the pivots or 9d as the case may be, provided suitable extraction pressure responsive mechanism is provided to perform this function. The linkage shown in Fig. 1 is a simple and reliable mechanical expedient for obtaining the same result as would be obtained by shifting the pivot 9a.

The invention is applicable also to more complicated three-arm extraction governing systems, one of which is illustrated in Fig. 2. Here, similar components are indicated by like reference numerals as used in Fig. 1.

Referring more particularly to Fig. 2, it will, be seen that the inlet valve 1b has its valve stem pivoted at 15 to a floating lever 16, the right-hand end of which is connected to the three-arm pivot 90. The left-hand end of lever 16 is pivoted at 16a to a bell-crank 17 the other arm of which is pivoted at 17a to the actuating rod 18a of the extraction pressure governor 18. This governor is responsive by way of conduit 19a to the extraction pressure in conduit 19 which communicates withthe intermediate turbine section 1e. As with the governor of Fig. 1, the function of the three-arm lever 9 is :to open and close the inlet valve 1b and the extraction, valves 1d, 1 as a function of changes in load, while the extraction pressure governor 11 produces a differential movement of the inlet valve 112 as compared with -thatlof theesting ro ing link 'co ifld be' substitiitedfor the link IZb-whichin Fig. 2- conass 3,9560:

'5 trachea-valves 1d If,- by effecting rotation of the threeatnlever 9 abo" itsfiulcrunr pivot 9a. The addition of in e' edia' e turbine stage le r'e'quires'a second threearm levrshown' at 20; The'le'f-t-han'd arm of this lever iiinverse at 20a to the stem of extraction valve 1f,.and tiie'right han'd end is pivotedat 20b to'the stem of extraction-valve ldi The third arm carries a roller member 200 which engages a recess in a gu'ide-blockltli: carried an the actuating rod=182ro pressure governor 18. The" basic operationof a multiple three-arm governing this type will be seen from the above-men- E cson etaL- Patent 2-,1 l1--,420.

' In the governor of} Fig. 2, the present invention is'inc'orp'or ih'the" linkage whichconnects the right-hand piv "9d f"tliie'e aifrh lever 9 with the common point or fuleruth pivot z'flti of the second--th'reearm lever 20; This compensator linkage,-identified generally by the reference numeral 2-1 comprisesa linl- 21a pivoted at 9d to'the firsttliree-a'rrti lever; 9am to an intermediate portion of wiever 21b; the right-hand end of which is" carried on an GfhlEtnih' 21c.- The-lefbhand end is pivoted at 21d "link ZI'-vvhichisdn-turn pivoted 'at'21f to the leftliand 'nd one s'eond lever 21g; Link 21h is-piv-oted' at 211 to lever 21g, andcar-r-ie's at its lower end the common rate-rum 2M1 The right-hand end of lever 21g is conncct'ed By 'a" link 21- to a" bell-crank 21k the other arm os w'm spivoted -at i'll m to-the'pres'sure governor actu- 18a'; The general similarity of the compensator linkage 21 to'the linkage 12 in Fig. 1 will be appar'nti- Theoiaefation or a multiple three-arrn governing systenrbecemesextremay complex as the number of turbine sectiensihereases beyond- 2, because of the many; interrelatedfactdrs; a'nd it isbelie'ved unnecessary to describe in complete detail theoperation of the multiple threea rin-ine'chanismshown inFig. 2. The basic operation is as 'd'escrihed in' Patent-2,11 l-,420;' and the compensator ineohani'sin-21 operates-in the same manner as the linkage 12 in Fig. 1. However, by comparison of the structures-of Fig'ss- 1'- and -2 herein, the following points of similarity will lie-observed; In each case, the modifying link'a'ge ls inco'r porated in the mechanism which positions 'v'ertieall'y the fulcrunipivot of the three-arm lev'e'r contrailing the wosteamvalves immediately upstream from the turhiriesection having the uncontrolled extraction (that "is-, valves-1 f and-1d in Fig. 2 an'd'valves 1H and 1b in Figr 1 The r'nodifyin'g' effect is' produced in accordance with changes iii-the pressure of the-controlled extraction stage -immec lia'tely up's't reamfrom the uncontrolled entractionstaget- The end-result of the m'odifying e'fiec't i's that the effective lever ratio of the three-arm d s'o astop'r'od'uce increased movement of the h i'gher-tpre's'shre valvemeans'for a given change -in-posip ess'ure valve,

While'onl y-a limitecl nu'mber of embodiments of the invention are described herein, it will-beapparenttothose ki ned innthe art that ma'ny' other variants arep'ossible. 'Fo nst nc if-ir'itheiarrange'ment of Figt 2 the'r'e w're another feedvvater heatersupplied with heatingflu'id from the inteiInediate tiirbi-nestage1e, then a secondm'odifye in accordancewith tha-tshown at12in Fig. 1

oint d 'of the fiyball governor-with the a ofthe first three-arm lever. I'n'other Bord-s; it is necessary to provide this modifying means in the action nf-each three-arm lever which controls" tnetwo n'iine'diat'ely "upstream from the sect'ion' of the turm which an uncontrolled extraction conduit takes flnida the -pnina-ry'appjlication'for th'ednvention' debd ereinhhs be'en forstea'm turbine'plants where theuncontrolledextraction steam is used in-a-feedwater hemes; the invention n-lay i also be applied to' extraction turbines uncontrolled eXtr-action is tis'ed for other? atinga urposes; such as anotherchemical process analtigous to" that represented by; 4a, where the exhaust steam firom: this consumer isreturned eventually as condensaite' to: the holler. The" feedw-aterheater 6 maybe either? an- Open type,- in which the steam accomplishes itszlieatingifunetion by merely being mixed with the con densate;.- or; at clbsed" typer in whic-h the' condensate being heatedpasss:thfough'tubes and theheating steam flows over the outside of-the tubes, with the result that the heating steam is eventually condensed" and returned to the boiler with? the-other condensate. The principles of the invention are alsoapplicable to extraction turbine. governors of" other types; such as those having hydraulic. or other power ac'tuit'ed components equivalent to the mechanieal; linkage means. disclosed herein.

It 'will'beseen tliat the invention provides simple and etfectivenieans for niodifyingd-the action of the basic three arm=governor-so*as toPre'nder it applicable to extraction turbines havingone dr nio'reuncontrolledextraction com duits supplying feedwater heaters:

Ibis, of course,-desired-tocover by the appended claims all=- suchltnodifications'ias fall within' the true spirit and scopeof-the invention;

WhatI claim as'i'new and-desire to-secure by Letters Patent in -the" United State's Sis:

In aggoveriiingvsystem for a multiple section elastic fluid-turbinehaving an inlet valve admitting motive fluid to='ai',hig'he'r:pressure turbine section and at least one extraction-valveadmitting-motive fiuidtoa lower pressure turbine se'ctiomfrom Isaidhigher pressure section, first conduit-means eittra'c'ting elastic fluid-from said higher pressureset'z'tionlupstrean'rfrbm said extraction valve'at variable-rates; with autt'arnatic powermeans positioning said valvesboth in the closingidirection or both in the opening direction ase-afunction 'of turbine'speed and positioning oneof said valves-intheclosing direction and the other in' th'e openingidirection as a tun'ction of changes in extraction pressu'i'ein said first conduit,-the combination of asecond-extraction conduit supplyingelastic fluid to a consume'r at vatr-iable rates from said lower pressure turbine sectiondownstre'am from s'aid -extraction valve, and means modifying. the a'ctionfiof said" automatic power means to movethe'inletvawe :an'd the extra'ction valve both in the closing directionkor both=in the opening direction by increments which are a function of' changes of pressure in said first extraction'conduit to-h'old substantially constant the rnechanical'powr output of the turbine irrespective of variations-in the amount of elastic fluid extracted from said firstand second "conduits.

2'; In'a=governing systemfora multiple section elastic fluid tui'bine h'aving an inlet-valve' admitting-motive fluid to'a first hi'gh pi'essur'e turbine sectionand at least one extraction valve-admitting m'otive'fluid' to a second lower pressure turbinesectioninseries with said first section, a controlled extraction condu'it' extracting fluid at variable rates' froni the first t bine section upstream from said extraction: valve, Y, with t automatic servo meansconnected to position said-lvalvesin the same direction as a function of turbine speed and-in o posite directions as a function of 'cha'ng'es in pr'essure -in the controlled extraction conduit; the combination ofi an uncontrolled extraction conduit supplyihg finid at 'variablerates to a consumer from a location in tlie second tnrbine' section downstream from saidiektraction valve'; and means-modifying the action of said 'servo 'means 'to 'c'a'u'se' said valves both 'tomove in the 'openingl'direction y anincre'ment independent ofany change'i li'rb'ine-='spe'ed and-proportionalto adecrease in pressni'e'imsaiddontrolledextraction conduit to hold substantially'ooitstafit the mechanical power output of the turbine regardless oiiv'aiiations inthe amount of controlled andiunc'ontr'ol d extraction.'

3. Inlaning system" for a multiple sectionelastic fluidtnrbiiiehaving an..=inlet-valve =admitting: motive fluid to a fitsthigh)iptbssilre turbine section and an extraction valve admitting "o'tive' aid to a' s'econd lower pressure "first section,- withcontrolled extraction conduit means removing elastic fluid from the first section at a location upstream from said extraction valve at variable rates and servo means connected to position said valves in the same direction as a function of turbine speed and in opposite directions as a function of changes in pressure in said controlled extraction conduit, the combination of an uncontrolled extraction conduit supplying elastic fluid to a consumer at variable rates from said second turbine section downstream from said extraction valve, and means positioning said valves both in the opening direction by increments proportional to decrease in said controlled extraction conduit pressure resulting from changes in the amount of fluid withdrawn through said controlled and uncontrolled extraction conduits to hold substantially constant the mechanical power output of the turbine regardless of variations in said fluid extraction.

4. In a governing system for a multiple section elastic fluid turbine having an inlet valve admitting motive fluid to a first high pressure turbine section and an extraction valve admitting motive fluid to a second lower pressure turbine section from said first section, with controlled extraction conduit means removing elastic fluid from the first section upstream from said extraction valve at variable rates and means connected to position said valves in the same direction as a function of turbine speed and in opposite directions as a function of changes in pressure in said controlled extraction conduit, the combination of an uncontrolled extraction conduit supplying elastic fluid at variable rates to a consumer from said second turbine section downstream from said extrac tion valve, and means for increasing the rate of opening movement of the inlet valve relative to the rate of opening of the extraction valve as a function of decreasing pressure in said controlled extraction conduit to hold substantially constant the mechanical power output of the turbine irrespective of variations in fluid extraction.

5. In a three-arm lever type governing system for a multiple section elastic fluid turbine having an inlet valve admitting motive fluid to a high pressure turbine section and an extraction valve admitting motive fluid from the high pressure section to a lower pressure section, with controlled extraction conduit means removing elastic fluid at variable rates from the first section at a location up stream from said extraction valve and three-arm lever means having a fulcrum pivot connected to speedresponsive means to position said valves in the same direction as a function of turbine speed and pressure responsive means connected to cause said lever to position said valves in opposite directions as a function of changes in pressure in the controlled extraction conduit, the combination of an uncontrolled extraction conduit supplying elastic fluid at variable rates to a consumer from the second turbine section downstream from said extraction valve, and servo means responsive to pressure changes in the controlled extraction conduit for moving said fulcrum pivot of the three-arm lever in the valve-opening direction as a function of decreasing controlled extraction pressure to increase the rate of opening movement of the inlet valve relative to opening movement of the extraction valve to hold substantially constant the mechanical power output of the turbine irrespective of variations in fluid extraction.

6. In a three-arm lever type governing system for a multiple section elastic fluid turbine having an inlet valve admitting motive fluid to a first high pressure turbine section and an extraction valve admitting motive fluid to a second lower pressure turbine section, with controlled extraction conduit means removing fluid at variable rates from the first section upstream from said extraction valve and a three-arm lever with a fulcrum pivot connected to speed-responsive means to position said valves in the same direction as a function of turbine speed and pressure-responsive means connected to cause said lever to position said valves in opposite directions as a function of changes in pressure'in said controlled extraction conduit, the combination o f'an uncontrolled extraction conduit supplying elastic fluid at variable rates to a consumer from said second turbine section downstream from said extraction valve, and means responsive to pressure in said controlled extraction conduit for mov ing the fulcrum pivot of the threearm lever in the valveopening direction by an increment proportional to decrease in controlled extraction pressure to increase the rate of opening of the inlet valve relative to the rate of opening of the extraction valve as a function of decreasing pressure in the controlled extraction conduit in order that mechanical power output of the turbine will remain substantially constant irrespective of variations in fluid extraction from said controlled and uncontrolled extraction conduits.

7 In a three-arm lever type extraction governing system for a multiple section elastic fluid turbine having an inlet valve controlling the admission of motivefluid to a first 'high pressure turbine section and an extraction valve admitting motive fluid from the first turbine section to a second lower pressure turbine section, with a controlled extraction conduit connected to remove elastic fluid at variable rates from the first turbine section at a location upstream from said extraction valve, and a three-arm lever with turbine speed-responsive means connected by first linkage means to a fulcrum pivot of the lever for positioning the fulcrum as a function of turbine speed and one arm connected to position the inlet valve, another arm connected to position the extraction valve, and pressure-responsive servo means connected to the third arm for rotating the three-arm lever about said fulcrum pivot in accordance with pressure changes in said controlled extraction conduit, said speedresponsive and pressure-responsive means acting on the three-arm lever to position both of said valves in the same ldlYCtlOH as a function of rotor speed and in opposite directions as a function of controlled extraction conduit pressure, the combination of an uncontrolled extraction conduit supplying fluid at variable rates to a consumer from said second turbine section downstream from said extraction valve, and second linkage means connected to move in response to pressure changes in said controlled extraction conduit and connected to modify the action of said first linkage means to position the fulcrum pivot of the three-arm lever in the valve-opening direction by an increment proportional to decrease in controlled extraction pressure to increase the rate of opening of the inlet valve relative to the rate of opening of the extraction valve as a function of decreasing controlled extraction pressure.

8. In a governing system for a multiple section elastic fluid turbine having an inlet valve admitting motive fluid to a first high pressure turbine section and an extraction valve admitting motive fluid from said first section to a second lower pressure turbine section, with first extraction conduit means removing elastic fluid at variable rates from the first section upstream from said extraction valve, the combination of a three-arm lever member connected to position the inlet and extraction valves in the same direction as a function of translational movement of the lever and in opposite directions as a function of pivotal movement of the lever about a fulcrum, means responsive to turbine speed for effecting translational movement of the lever to open and close the valves together, means responsive to pressure in said first extraction conduit for effecting pivotal movement of the lever about said fulcrum to position the valves in opposite directions, and linkage means for effecting an additional increment of translational movement of the lever to increase the rate of opening movement of the inlet valve relative to the opening of the extraction valve as a function of decreas ing pressure in said first conduit to hold substantially constant the mechanical power output of the turbine irrespective of changes in extraction flow.

' '11 7 Q In, a governing. system for a multiple section elastic turbine having a first inlet valve admitting motive fluid to a first .highg pressure turbine section, a second valve; admitting motive; fluid from the first turbine section to a second intermediate pressure turbine section, a third valve admitting motive fluid from the second turbine section to a thirdlow pressure turbine section, a first extraction conduit connected to supply fluid to a consumer at variable. rates from the first turbine section at a. location upstream from said second valve, 21 second extraction conduit connected to remove elastic fluid at: variable rates from the second turbine section upstream from said. valve, a first three-arm lever member with a fulcrum connected to be positioned by a turbine speed-responsive device and having one arm connected to position said first valve, another arm connected to first pressure-responsive means to rotate said first lever abdutsaid fulcrum in. accordance with changes of pressure in the first extraction conduit, and a third arm connected by first. linkage means to the fulcrum pivot of a-useconcl threeaarmlever having one arm connected to position the second valve and another arm connected to position the third valve, and second pressure responsive means connected to position the third arm of the second lever as a function of changes of pressure in the second extraction conduit, said speed-responsive device positioning the fulcrum of said first three-arm lever as a function of turbine speed to cause all three valves to move in the same direction as a function of turbine speed, the combination of a third extraction conduit connected to remove elastic fluid at variable rates from the third turbine section downstream from said third valve, and means responsive to pressure changes in said second extraction conduit for modifying the action of said first linkage means to move the fulcrum of said second three-arm lever in the valve-opening direction in accordance with a decrease in pressure in said second extraction conduit.

References Cited in the file of this patent UNITED STATES PATENTS 2,095,860 Ericson Oct. 12, 1937 2,111,420 Ericson et a1 Mar. 15, 1938 2,520,568 Sederquist Aug. 29, 1950 2,523,078 Wales s Sept. 1-9, 1950 

